The interplay of pairing with the different terms of the residual interaction is explored for the low-lying energy levels of semi-magic nuclei from the point of view of spectral statistics. The reduced degree of chaoticity present in this nuclei is shown to be directly related to the strength of the pairing interaction with respect to the total residual interaction. On the contrary, the pairing strength does not influence the spectral statistics near the ground state for nuclei with both neutrons and protons outside closed shells.